Continuous flow type hydraulic power steering mechanism



w. D. NELSON 2,915,044

CONTINUOUS FLOW TYPE HYDRAULIC POWER STEERING MECHANISM Dec. 1, 1959 2Sheets-Sheet 1 Filed Feb. 28, 1955 w. D. NELSON 2,915,044

CONTINUOUS FLOW TYPE HYDRAULIC POWER STEERING MECHANISM 2 Sheets-Sheet 2(far/regs H/ I I K fl W l m. W1 I J Dec. 1, 1959 Filed Feb. 28, 1955CONTINUOUS FLOW TYPE HYDRAULIC POWER STEERING MECHANISM This inventionrelates to an improved hydraulic actu- United -States Patent ator, of atype which is particularly adapted for use in connection with powersteering mechanism, and is a continuation-in-part of mycopendingapplication, Serial No. 340,458, filed March 5, 1953, nowPatent No. 2,703,149, dated March 1, 1955.

. It is an object ofthe present invention to provide a.

hydraulic actuator in which the input and output shafts are aligned witheach other.. This aligned relationship of the elements greatly enhancesthe utility of the device,

since the device may then be inserted at a'suitable point in a straightsection of shaft, without requiring change of design of the originalmechanism to which the hydraulic actuator is applied, such,.forinstance, the steering shaft of an automobile. 3 t f A further object ist'o provide a hydraulic actuator which provides a positive mechanicalconnection between the 'inputand output shafts, thereby permitting operation of the mechanism in case of failure of the hydraulic pressure.Asapplied to hydraulic steering mechanism, this is of particular-utilitysince it permits the' operator to turn the" front wheels even though thevmotor is turned off, as when thecar is parked.

A further objectis to provide a power steering mechanism having improvedresponsiveness and sensitivity and one which is-irreversible in action,and which is charac- 'te'rizedsby extremesimplicity of construction andlow manufacturing cost of this type. f 7

Other objects, features and advantages will become apparent as thedescription proceeds.

as compared with prior art devices With reference now to the drawings inwhich like ref-, erence numerals designate like parts? i t Fig. -1 is alongitudinal section through a'preferre embodiment of my invention;

Fig. 2. is a vertical transverse section taken along line 2-2 ofFig.,,l, 'showingthe cylinder portion;

, Fig. 3- is'a,vertical transverse section taken along line i ;3-'3 ofFig. 2, showing the valve portion;

. Fig. 4 is a leftejnd view of Fig 1, taken along line Fig. 6 is aviewsimilar to Fig. 1, but showing a modification;

Fig. 7 is a vertical transverse section taken along line Fig. 5 is ahorizontal section taken along line 5+5 of Fig. 8 is a verticaltransverse section taken along line 88 of'Fig. 1. p

With reference now to Fig. 1, the hydraulic actuator comprises a tubularmember 10, the ends of which fit into and. are enclosed. by end pieces 11 and 12. The

assembly is held together by tie bolts 13 and nuts 14. The elements 10,11 and 12 provide an enclosure, the '1 leftend iofzwhich comprises acylinder chamber or-portion- 15, and the rightzend of which comprises avalve chamber or portion 16, the two" portions" being separated l1 1:

2,915,044 Patented Dec. 1, 1959 from each other to define chambers bymeans of a rotatable disk 17.

An output shaft '18 is journaled in the end piece 11 and extends intothe cylinder chamber 15, the disk tl-7 being. secured to, or forming apart of the shaft 18, so that the two will rotate with each other.Suitable mechanism can be connected to the output shaft 18, and in thecase of power steering mechanism, this con-- nection is made by pitmanarm 19 which can be connected directly to a suitable drag link or thelike.

The cylinder and piston mechanism herein described can be'referred to asa butterfly typeof cylinder and piston or as an oscillating motor of thecontinuous flow type. Secured to, or formed integral with the tubularmember 10 is a stationary divider 20 which extends from the tubularmember up to the output shaft 18. Secured tive of whether it isexpanding or contracting in volume.

Suitable inlet means may be provided for each of the expan'siblechambers I'Saand 15b, such as the inlet ports and nipples 22 and 23shown in Fig. 4, the ports being formed in the end wall 11, and thenipples or other connecting means being threaded into the ports.

Each of the inlet means 22 and 23 is connected to a source of hydraulicpressure, such as separate pumps, not shown, and which form a closedsystem which includesthe return port and nipple 28, shown in Fig. 1.Ifthe'. pressure in the expansible chamber 15a is or becomes greaterthan the pressure in chamber 1517, then the vane 21 and the outputshaft. 18, will move to the right or in the clockwise direction, asviewed in Fig. 2, and vice-'versa. In other words, in this butterflytype of cylinder, the butterfly piston and the output shaft are rotated.I

The valve means comprise a valve member 25, in the form of a disk, whichis secured to or formed integrally with an input shaft 26 which isjournaled in the end member 12. The disk '25 is provided with a slot 27which, a

in normal position, that is, during pressure equilibrium, registers witha portion of each of the outlet ports 24. In otherwords, the width ofthe slot 27 may be equal to, or" somewhat less than the distance betweenthe port centers, as shown in Figs. 5 and 8. V

In operation, it will be seen from an inspection of Figs. 5 and 8, thatas the valve disk 25 is rotated toward the left, as viewed in Fig. 8,the open port area of port-24a willbe cut down and the open port area ofport 241) will be increased. This causes the pressure in expansiblechamber 15a to increase andthe pressure in expansible chamber 15b todecrease, with the result that the vane 21, and the output shaft 18 willrotate in the counterclockwise direction, thus following thecounterclockwisemovement of the shaft 26 and the valve disk In otherwords, rotation of the input shaft 26 merely shifts the open port area,or regulates the valve, and, therefore, requires no substantial inputtorque. On the other hand, the torque imparted to the output shaft 18 isvery substantial, depending upon the vane area and the pressuredifferential. I

A suitable thrust bearing 30 may be provided between the rotatable disk17 and the valve disk 25, and may be countersunk into one of theseelements so as to minimize the clearance between these elements as muchas possible, the clearance shown being considerably exaggerated. Minimumclearance is desirable in order to secure proper valve action. may beinterposed between the valve disk 25 and the end piece 12. The thrustbearings 30 and 31 materially reduce the load on the input shaft, andradial bearings may be inserted eleswhere, as needed.

Suitable means may be provided to prevent outward movement of the outputshaft 18, such as the lock ring 33, shown in Fig. 1.

Although a certain amount of free movement of the input shaft withrespect to the output shaft is necessary Similarly, a suitable thrustbearing 31,

for valve operation, as pointed out above, an important feature of thepresent invention is the fact that the coaxial arrangement of the inputand output shafts permits a mechanical connection to be provided betweenthe two which will enable the input shaft to drive the output shaft whenthere is no hydraulic pressure, that is, when the supply means isinoperative.

Thismeans comprises a lost motion connection between the two, best shownin Fig. 8. The output shaft 18 projects beyond, or to the right of, thevalve disk 25, and is slabbed as shown in Fig. 8, to provide avpreferred arrangement is shown in Fig. 8 in which the r 1 end walls ofthe opening 35 are arcuate and closely fit the radius of the pilot, andin which the side walls are generally hour glass shape to permit theproper distribution of stress, when the input shaft drives the outputshaft. It is apparent that the valve member 25 needs to extend only asuflicient distance on either side of the slot to provide eifectivevalve action, although the valve member is shown herein as being in theform of a disk to provide sufficient wall thickness around the enlargedopening 35 and to insure proper distribution of stress.

In the modification shown in Figs. 6 and 7, those parts which aresubstantially identical to the parts shown in Figs. 1 6 and 8 areidentified by the same reference numeral but primed, as employed inconnection with the first embodiment.

In Figs. 6 and 7, the cylinder chamber 15 is closed at its right end bya stationary wall 40, rather than by the rotatable disk 17 of Fig. l.The'stationary wall 40 may be in the form of an end plate whichcooperates with the tubular member 10 in the same manner as end plate12. The wall member 40 is provided with two series of outlet portsarranged in concentric arcs with respect to the axis of the output shaft18, an outer series of ports 41 and inner series of ports 42. The valvememher 43 may be substantially the same as the valve disk 25, and ismounted on an input shaft 21' and is provided with a slot 44. However,as shown in Fig. 7, the walls of the slot 44 are preferably radiallydisposed, and the width of the slot is somewhat-greater than the widthof the vane 21'. The valve member 43 is enclosed by a suitable housing45, the housing being suitably secured to the stationary wall 40. Thereturn port and nipple 28' are formed in and secured to the housing 45.I

The separate ports 41 of the outer series are staggered with respect tothe separate ports 42 of the inner series,

and the distance between adjacent ports in thesame series 1s less thanthe port diameter. Thus, the port area provided by one series overlaps,at all points, the port area provided by the other series, to providethat which is referred to herein as a continuous port area, and asexplained ing reater detail in the aforementioned copending application.

The open port area is that part of the port area which is not covered bythe valve disk 43; or, to put is conversely, that part of the outletport area which is exposed by the slot 44. The depth and Width of theslot 44 may desirably be such that when the parts are in the position ofequilibrium shown in Fig. 7, and symmetrically disposed with respect toone of the ports 41, the slot will expose substantially one-half of thearea of the adjacent ports 41, and a portion of the port area of twoadjacent inner ports 42. However, there may be substantial variation inthe dimensions indicated without affecting the operation and withoutdeparting from the spirit of my invention.

In the modification, a suitable lost motion connection may be providedbetween the output shaft 18 and the input shaft 26', similar to thatshown in Fig. 8, and identified by the reference numerals 34 for thepilot and 35 for the recess in Fig. 6. However, in the modification, theclearance between therecess 35 and the pilot 34' may be somewhatincreased over that shown in Fig. 8, to permit a greater degree of lostmotion, in those instances in which it is desired to take advantage ofthe more rapid action provided by the use of a continuous series ofports in a stationary wall member as contrasted with the provision ofonly one port for each expansible chamber, when the ports are located ina rotatable wall portion, as shown in Fig. l. However, in eitherembodiment, the rapidity of action can be increased by increasing thediameter of the outlet ports 24, or 41 and 42.

In eithermodification, a high degree of sensitivity can be attained.Furthermore, in spite of the mechanical connection between the input andoutput shafts, the action is substantially irreversible since the lostmotion connection requires a substantial degree of movement of theoutput shaft before corresponding motion is imparted to the valve means,and this motion of the output shaft is in a direction opposite to thedirection of pressure differential created by such movement.

To summarize the operation, which has been described in connection withthe description of the various parts, rotation of the input shaft 26, or26, will cause a shifting of the discharge area of the ports 24 or 41and 42; that is, the open port area will be shifted. Assuming that twopumps, not shown, each provide equal delivery at equal pressures to theinlet ports 22 and 23, the pressure within each of the expansiblechambers 15a and 15b will be determined by the discharge or open portarea provided for each chamber, thus building up a pressure differentialwhich actuates the output shaft 18 or 18.

The present invention provides a construction in which the input andoutput shafts are aligned with each other, thereby considerablysimplifying the application of or installation of the hydraulic actuatorto existing mechanisms.

Furthermore, the alignment of the shafts permits a simple type ofmechanical connection to be made between the two shafts so that themechanism in which the actuator is installed will be operative eventhough the pressure supply means is inoperative.

Although I have shown and described herein only preferred embodiments ofmy invention, it will be understood that various modifications andchanges ,may be made in the constructions shown without departing fromthe spirit of my invention as pointed qout'in theappended claims.

I claim:

1. A- hydraulic actuator of the butterfly cylinder type a butterflycylinder, .Said end wall means. comprising a stationafy wall memberforming a part of said butterfly cylinder providing means, a butterflypiston rotatably mounted in said butterfly cylinder and serving todivide the interior of said cylinder into two expansible chambers, aninlet for each chamber, outlet port means located in said end wallmeans, and comprising a series of ports formed in said stationary wallmember and arranged in a circular arc to provide passageways for eachof'said expansible chambers, valve means cooperating with said outletport means to regulate the fluid pressure differential between saidexpansible chambers, said butterfly piston including a vane and anoutput shaft, and said valve means including an input shaft axiallyaligned with said output shaft, one of said shafts being slotted and theother being provided with a slabbed portion received Within said slottedshaft and being narrower than the same to provide a lost mo'tionconnection between said aligned input and output shafts.

2. A hydraulic actuator as claimed in claim 1 in which said port meansincludes a second series of ports formed in said stationary wall memberand concentrically arranged in a circular arc with respect to said firstseries, the apertures of each series being staggered with respect toeach other so as to provide a continuous overlapping port area, and inwhich said valve means includes a valve port having a width dimensiongreater than the width of said vane whereby a continuous open port area,of a width greater than the width of said vane, is provided by thecooperation of said valve means and said port means.

3. A hydraulic actuator of the butterfly cylinder type comprising meansproviding a butterfly cylinder, a butterfly piston rotatably mounted insaid butterfly cylinder and serving to divide the interior of saidcylinder into two expansible chambers, an inlet for each chamber, saidbutterfly piston including an output shaft and a disk mounted on saidoutput shaft and rotating therewith and cooperating with the peripheralwall of said butterfly cylinder to define said expansible chambers,outlet port means formed in said disk and comprising one passageway foreach of said expansible chambers and partially blocking both of saidpassageways when in normal position, and valve means cooperating withsaid port means to regulate the fluid pressure differential between saidexpansible chambers, said valve means including an input shaft alignedwith said output shaft, and means maintaining said input shaft in axialalignment with said output shaft so that proper operating relationshipcan be maintained between said valve means and said port means.

4. A hydraulic actuator as claimed in claim 3 in which said butterflypiston is provided with a slabbed pilot, and in which said valve meansis provided with an enlarged I hour-glass shaped opening receiving saidpilot, said pilot and said opening providing a mechanical connectionpermitting a limited amount of lost motion.

5. A hydraulic actuator comprising means providing a cylinder chamberand a valve chamber and including a wall member separating said cylinderchamber from said valve chamber, an output shaft extending into saidcylinder chamber, a divider member extending between the wall of saidcylinder chamber and said shaft, and being secured to said cylinderchamber, said shaft being rotatably mounted with respect to saidcylinder chamber and said divider, a vane extending between said shaftand the wall of said cylinder chamber and being secured to said shaftand rotatable therewith, said vane and said divider cooperating todivide the interior of said cylinder chamber into two expansiblechambers, an inlet for each chamber, a plurality of outlet portsextending through said wall member and providing communication betweeneach expansible chamber and said valve chamber, an input shaft extendinginto said valve chamber, and a valve member carried on said input shaftand disposed adjacent to said wall member to block off portions of saidoutlet ports, said valve member also providing a valve port aligned withother portions of said outlet ports, whereby angular displacement ofsaid valve member with respect to said wall member will decrease theport area communicating with one of said expansible chambers andsimultaneously increase the port area communicating with the other tocreate a pressure diflerential causing actuation of said butterflypiston.

6. A hydraulic actuator comprising means providing a cylinder chamberand a valve chamber adjacent thereto and including a common wall memberseparating said cylinder chamber from said valve chamber, an outputshaft extending into said cylinder chamber, a divider member extendingbetween the wall of said cylinder chamber and said'shaft, and beingsecured to said cylinder chamber, said shaft being rotatably mountedwith respect tosaid cylinder chamber and said divider, a vane extendingbetween said shaft and the wall of said cylinder chamber and beingsecured to said shaft and rotatable therewith, said vane and saiddivider cooperating to divide the interior of said cylinder chamber intotwo expansible chambers, an inlet for each chamber, a plurality ofoutlet ports extending between and providing communication between eachexpansible chamber and said valve chamber, an input shaft extending intosaid valve chamber, a valve member carried on said input shaft anddisposed adjacent to said wall member to block off portions of saidoutlet ports, said valve member also providing a valve port aligned withother portions of said outlet ports, whereby angular displacement ofsaid valve member with respect to said wall member will decrease theport area communicating with one of said expansible chambers andsimultaneously increase the port area communicating with the other tocreate a pressure differential causing actuation of said butterflypiston, and a lost motion connection between said input shaft and saidoutput shaft providing direct mechanical connection between the two incase of failure of hydraulic pressure.

7. A hydraulic actuator comprising means providing a cylinder chamberand a valve chamber, an output shaft extending into said cylinderchamber, a divider member extending between the wall of said cylinderchamber and said shaft, and being secured to said cylinder chamber, saidoutput shaft being rotatably mounted with respect to said cylinderchamber and said divider, a butterfly piston in the form of a vaneextending between said shaft and the wall of said cylinder chamber andbeing secured to said shaft and rotatable therewith, said vane and saiddivider cooperating to divide the interior of said cylinder chamber intotwo expansible chambers, an inlet for each chamber, a rotatable disksecured to said output shaft and separating said cylinder chamber fromsaid valve chamber, two outlet ports extending through said disk, onefor each expansible chamber, an input shaft extending into said valvechamber, and a valve member carried on said input shaft and disposedadjacent to said disk to block off portions of said outlet ports, saidvalve memher also providing a valve port aligned with other portions ofsaid ports, whereby angular displacement of said valve member withrespect to said disk will decrease the port area communicating with oneof said expansible chambers and simultaneously increase the port areacommunicating with the other to create a pressure differential causingactuation of said butterfly piston.

8. A hydraulic actuator comprising means providing a cylinder chamberand a valve chamber, an output shaft extending into said cylinderchamber, a divider member extending between the wall of said cylinderchamber and said shaft, and being secured to said cylinder chamber, saidoutput shaft being rotatably mounted with respect to said cylinderchamber and said divider, a butterfly piston in the form of a vaneextending between said shaft and the wall of said cylinder chamber andbeing secured to said shaft and rotatable therewith, said vane and saiddivider cooperating to divide the interior of said cyl- '7 inder chamberinto two expansible chambers, an inlet for each chamber, a rotatabledisk secured to said output shaft and separating said cylinder chamberfrom said valve chamber, two outlet ports extending through said disk,one for each expansible chamber, an input shaft extending into saidvalve chamber, a valve member carried on said input shaft and disposedadjacent to said disk to block off portions of said outlet ports, saidvalve member also providing a valve port aligned with other portions ofsaid ports, whereby angular displacement of said valve member withrespect to said disk will decrease the port area communicatingwith oneof said expansible chambers and simultaneously increase the port areacommunicating with the other to create a pressure diiferential causingactuation of said butterfly piston, and a lost motion connection betweensaid input shaft and said output shaft providing direct mechanicalconnection between the two in case of failure of hydraulic pressure andserving to maintain said valve member centered in said valve chamber.

9. A hydraulic actuator comprising a tubular member and two end piecescooperating therewith, a butterfly piston assembly disposed within saidtubular member and comprising an output shaft journaled in one of saidend pieces, a vane on said output shaft, a disk extending between saidoutput shaft and said tubular member and dividing said tubular memberinto a cylinder chamber and a valve chamber, and a slabbed pilotextending beyond said disk, a divider member secured to said tubularmember and extending into engagement with said shaft, said divider andsaid vane cooperating to divide.

the interior of said cylinder chamber into two expansible chambers, aninlet for each chamber, two outlet ports, formed in said disk at pointsimmediately adjacent said. vane and on opposite sides thereof, one foreach cx-- pansible chamber, an input shaft journaled in the other one ofsaid end members, a valve disk secured to said input shaft, a valve portextending through said valve, disk and having a width equalsubstantially to the distance between the centers of said outlet ports,said input shaft being aligned withsaid output shaft, and a non-circularopening formed in the face of said valve disk and receiving said slabbedpilot to provide a lost motion connection between said input shaft andsaid output shaft,v said valve disk being centered by said slabbed pilotto maintain proper operating relationship between said valve port andsaid outlet ports.

ReferencesCited in the file of this patent UNITED STATES PATENTS 821,398Bergesen May 22, 1906 1,859,333 Josephs May 24, 1932 2,020,847 MitereffNov. 12, 1935 2,481,426 Hull Sept. 6, 1949 2,735,406 Britton Feb. 21,1956 FOREIGN PATENTS 406,934 Germany Dec. 4, 1924 854,278 Germany Nov.4, 1952

